UBIQUITOUS STRUCTURES RESPONSIBLE FOR IGE CROSS-REACTIVITY BETWEEN TOMATO FRUIT AND GRASS-POLLEN ALLERGENS

The simultaneous presence of IgE reactivity to tomato fruit and grass pollen allergens is evident in many patients with allergy and may be c aused by cross-reactivity. Using sera from polysensitized patients wit h a positive enzyme allergosorbent rest (EAST) result (score >2), we t ested reactivity to both allergen sources. IgE reactivity against both extracts was demonstrated in eight serum samples, and cross-reactivit y was confirmed by the EAST inhibition assay. The structures responsib le for this cross-reactivity were identified by Western blotting: five of the eight serum demonstrated a 16 kd protein in both extracts, whi ch was identified as profilin. Additionally, seven of the eight sera s howed IgE binding to epitopes on carbohydrate moieties, which containe d alpha 1,3 fucosylations. To determine the allergens of tomato fruit extract, we performed two-dimensional polyacrylamide gel electrophores is blotting. We were able to demonstrate one highly concentrated and a bout 20 weaker proteins possessing terminal fucose residues. These are similarly found in grass pollen extracts. It is therefore postulated that the cross-reactivity is affected by profilins and similar carbohy drate determinants. If carbohydrate structures can provoke IgE cross-r eactivity between phylogenetically distant species, such structures ma y play an important role in sensitization and mediator release. The ub iquitous nature of the IgE-binding determinants was studied by additio nal EAST inhibition tests with tomato allergen disks and extract from birch pollen, mugwort pollen apple and celery, leading to significant inhibitions among all these allergen sources. Epitopes exclusive to gr ass pollen and tomato have not been detected.